I have installed Ubuntu 12.04 LTS on my laptop and recently brought my software up-to-date (through Update Manager). Since the update, I can't use any of network services. During boot-up it shows messages like "waiting for network configuration" and "booting without network configuration", even though my Ethernet cable is plugged in. On the right upper corner, the icon for network connections doesn't exist anymore, so there's no WiFi either. Should I simply reinstall Ubuntu or is there some other way?